Polycarbonate build plate…. No bed heat Success!!!
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For the sake of always being on the same page we will refer to cupping as middle of plate upward and edges curling downward. and warping as the middle being down and the edges curling up
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I've ordered some PETG and ASA (did you tried it?) samples from rigid.ink, and the 60grit sand paper will arrive tomorrow, let see how much the post takes from UK to Spain. I will do the testing and come back when I get home…
Thanks!
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I have not tried ASA but I have been eying it from a couple vendors primarily 3dxtech and rogidink.
Dont forget to run that mesh bed without the build plate?
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Hi there,
I've done several mesh, all of them with a homing first, the nozzle without residues and a temperature of 120C in the nozzle (as recommended by DjDemonD for the Piezo sensor).
First, without PC, just the buildtak that I still have in my plate:
It seems that I will need to re-level a bit the bed, is not too bad but can be easily improved.
Second with the transparent PC sheet, the one that is "warped" as per your definition (corners up, center down), attached to the bed with 4 bulldog clips (2 in the front, 2 in the back, near to the corners)
Third one with the white PC sheet, this is the flattest one, no warp/cup is observed without bulldog clips. The mesh was performed with the 4 bulldog clips in the same position as before tough.
Here a comparison between both PC sheets, without bulldog clips:
The left one is the transparent (warped) one, you can easily see that the corner is upward, if I press the edges or the corners with my fingers, the sheet go down a bit. The right one is the white sheet, it's hard to see because is a bit bigger than the builtak, but I can assure you that is flat, I can press anywhere in the surface and it sheet don't move down.
Here you can see the warping as described before:
Both parts were printed with 3DCPI PETG, same parameters, and both in the transparent PC Sheet AFAIR (I need to test this with the white flat one, but as it's not enough sanded yet, if I use it, I cannot unstick the part… I will wet sand it tomorrow when the 60grit arrives and test it again). The nearest one is a Z motor mount, and you can easily see that the part is not flat, the other one is the half of a cylinder for the spool holder, and the bend is not too noticeable, however, if I press a bit in one side (like I'm doing for the picture), you can see it.
I will try to do tomorrow the proper sanding, the leveling and I've got more bulldog clips to put in the center too, let see if I can get a green height map :D.
Cheers!
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Okay so the first heightmap with buildtak, how is the buildtak secured? are you leaving the buildtak under the PC?
That first heightmap i see cupping…. I am curious if you still have cupping with the raw build plate.... any chance you can remove the buildtak, clean the surface and run another heightmap? of just the raw build plate then one again with the clear PC clamped without buildtak under it.
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The Buildtak is sticked to the surface by the auto-adhesive it came with, and I'm leaving it under the PC as I'm not sure I can remove it without ruining it… I will try today to remove it and I will run the mesh again. I've got more bulldog clips, will use them too.
Regards
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Ok, so I've removed the buildtak sheet (without ruining it… I think I still can use it if I want to) and I've wet sanded both PC sheets... the surface now feels different (not sure how to say it honestly), this is a picture of the white (flattest) one:
Left, the wet sanded side, Right the other side, with regular sanding (I just wet sanded one side to be able to compare).After removing the buildtak I ran a homing+mesh@120ºC with the clean alu surface:
Now, the white (flattest) PC sheet (again, homing+mesh@120ºC) with 4 bulldog clips, front and rear corners:
And the transparent (warped) PC sheet (same, homing+mesh@120ºC) with 4 bulldog clips, front and rear corners:
Now I'm gonna level the bed (without PC) and repeat the testing.
Cheers
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Interesting, your warped PC appeared to have similar results to the bed both show cupping one of the things you can do after you level your bed more, is experiment with clips in different places. I ran a lot of mesh bed routines until I found the ideal location for clips on my med since my bed isnt flat
When you say 120c are you talking about the nozzle or the bed? is the bed at 0?
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120ºC at the nozzle, as per DjDemonD recommendations, the bed is at 0 (room temp) always.
I've leveled the bed:
This is the bed without the PC (just the bed), I cannot adjust it better, as I can only set 5 screws (3 in the front, 2 in the back) due to the location of the Z motors (left and right, at the same place than the holes =_=) and the bed cables in the back (around the middle)Here is the white (flattest) one after leveling:
I will put some clips in the left and right side, and do the mesh again to see if it improves, and then I will do a print test…How much offset from the bed are you using?
Cheers
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Personally before printing I would run a bunch of mesh leveling routines on both the clear and white with different clip positions, then compare the results of the two. Your test earlier showed better results with the clear than the white but that could change after changing up clip placement. The cup of the clear sort of acts to your advantage because you cannot clip the middle of the bed…. though once sorted you might find that is the reason the prints end with cups because the clear is following the shape of your bed so the white, might work better.
Your wet sanding job looks great btw, that sheen before from the 120 is what I was talking about.... when the sheen comes back things start to stick too well and its time to resand... I try to have my sanding such that I rarely have to remove the clips to remove a print.
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After using 8 clips (2 front, 2 back, 2 left, 2 right) the leveling is… exactly the same xD
I will need to redesign the Z bed attach to allow me to add an adjustment screw… anyway, for the moment, I will need to rely in the RRF mesh algorithm to compensate this....
I will do some print tests and let you guys know.
Thanks!
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It seems, most of the mesh levelling problems could be avoided by using a thick base plate ( glass/mirror suddenly is a good option ) and a thinner PC sheet?
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Quick update.
Not sure if you're following the PrecisionPiezo thread, where I posted some accuracy testing I did, as I found something quite interesting IMHO. I'm obtaining an accuracy of 0.002mm doing 36 tests over the same point, which is awesome, however, if I do it after homing, I was obtaining a deviation of 0.07Xmm (70 microns) from the Z homing test. This caused that the first layer sometimes was too low (and squished the filament) and sometimes was too high (and it didn't stick for the circles). I tried several things for Z homing (home X, Home Y, move slowly to Z, G30, Home Z again), and during several tests I got a better deviation (around 10-15 microns from the Z Homing heigh) and a mean of 0.002 for the testing in the same point. I still need to do more testing to be confident about the repeatability of the measures, but this explains why I got some of my issues with PETG, where I was unable to un-stick it (too close from the bed!).
Last night I printed another PrecisionPiezo support mount (in my trusty PLA), using the white (flattest) PC sheet, and this is the result:
I just had a couple of minutes this morning to check the print, but so far, my impressions:
- Circles and details in the first layer were perfectly printed, with some under extrusion (more about this in the last bullet point)
- It was really easy to remove, the bigger one I was able to remove by hand, for the low height ones, I just bended a bit the sheet and both came off perfectly
- I couldn't observe any warping/cupping, but I will check it closely when I get home tonight.
- I couldn't see elephant foot either, but I will do more tests with different Z offsets.
- I've detected that I'm having under extrusion problems after retraction… I've checked and my bowden tube is a bit too short after I setup the new sensor, and is a bit tight, so I'm gonna replace it for a bigger new tube. I've also observed that my acceleration/speed settings are the default ones and seems to be too low for my setup, compared with the settings I used to have in marlin before, so I will adjust that too and test again.
I will do the adjustments and report back, but the problems with the extruder may explain my low performance printing PETG, meanwhile the defective sanding I did and the random Z homing heigh can explain why I wasn't able to remove sometimes the part (60-70 microns is "nothing", but can be the difference of a squashed PETG impossible to remove and a good one).
Cheers!
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@CaLviNx:
It seems, most of the mesh levelling problems could be avoided by using a thick base plate ( glass/mirror suddenly is a good option ) and a thinner PC sheet?
I am using mirror polished ceramic floor tiles 12mm thick silicone heater underneath (if i need heat) and a 3mm pc sheet held down with button magnets and that seems to keep everything flat enough.
That sounds like a sweet setup, can you post pics of how its done?
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Quick update.
Not sure if you're following the PrecisionPiezo thread, where I posted some accuracy testing I did, as I found something quite interesting IMHO. I'm obtaining an accuracy of 0.002mm doing 36 tests over the same point, which is awesome, however, if I do it after homing, I was obtaining a deviation of 0.07Xmm (70 microns) from the Z homing test. This caused that the first layer sometimes was too low (and squished the filament) and sometimes was too high (and it didn't stick for the circles). I tried several things for Z homing (home X, Home Y, move slowly to Z, G30, Home Z again), and during several tests I got a better deviation (around 10-15 microns from the Z Homing heigh) and a mean of 0.002 for the testing in the same point. I still need to do more testing to be confident about the repeatability of the measures, but this explains why I got some of my issues with PETG, where I was unable to un-stick it (too close from the bed!).
Last night I printed another PrecisionPiezo support mount (in my trusty PLA), using the white (flattest) PC sheet, and this is the result:
https://s20.postimg.org/ykbxijjul/PP1.jpg
https://s20.postimg.org/4460keybh/PP2.jpgI just had a couple of minutes this morning to check the print, but so far, my impressions:
- Circles and details in the first layer were perfectly printed, with some under extrusion (more about this in the last bullet point)
- It was really easy to remove, the bigger one I was able to remove by hand, for the low height ones, I just bended a bit the sheet and both came off perfectly
- I couldn't observe any warping/cupping, but I will check it closely when I get home tonight.
- I couldn't see elephant foot either, but I will do more tests with different Z offsets.
- I've detected that I'm having under extrusion problems after retraction… I've checked and my bowden tube is a bit too short after I setup the new sensor, and is a bit tight, so I'm gonna replace it for a bigger new tube. I've also observed that my acceleration/speed settings are the default ones and seems to be too low for my setup, compared with the settings I used to have in marlin before, so I will adjust that too and test again.
I will do the adjustments and report back, but the problems with the extruder may explain my low performance printing PETG, meanwhile the defective sanding I did and the random Z homing heigh can explain why I wasn't able to remove sometimes the part (60-70 microns is "nothing", but can be the difference of a squashed PETG impossible to remove and a good one).
Cheers!
I actually ended up with a situation like yours last night but I have too many variables in the fire and more testing needs to be done to be sure…. but heres the jist of what happened.... i upgraded to the lastest version of S3D .... loaded up a new roll of Taulman Blueprint... yes my bed is getting a little shiny but there were a lot of variables at play here too that the surface wouldnt account for how bad it was.... my extrusion was suddenly out of whack and i couldnt get it right before i gave up for the night... also my z was a bitch to get correct even with babystepping.... three failed prints all with the same exact issue.... complete welding to the bed, parts near impossible to remove.
I will do some more testing this evening to see if i can get to the bottom of what causes this.
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I've upgraded S3D too, although I won't use it until I fix all my issues, just to avoid the too many variables problem =_=, and then I will print couple of parts using both just to compare… I'm curious about the new bridging stuff, as in my experience, bridges in S3D were a mess compared with cure or slic3r...
Cheers
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Okercho, can you try printing an object with a large, flat base, to see if the "cupping" is still present? I suggest a 150-200mm circular profile, extruded a couple mm tall. In my experience, it is these types of prints that show the cupping the most. Especially hollow structures, eg the bottom surface of a hollow cylinder, where the surface area on the bottom occupies a large portion of the bed.
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I'm planning to do a case for the PanelDue7" in PETG once the extrusion problem is fixed, with that we should be able to check if the warped/cupping problem is still present… Hopefully I would be able to do during this weekend and let you guys know.
Cheers
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@bot:
Okercho, can you try printing an object with a large, flat base, to see if the "cupping" is still present? I suggest a 150-200mm circular profile, extruded a couple mm tall. In my experience, it is these types of prints that show the cupping the most. Especially hollow structures, eg the bottom surface of a hollow cylinder, where the surface area on the bottom occupies a large portion of the bed.
When you say that the stresses transferred to the print from a cupped bed held flat will result in a cupping effect in the print or do you mean a warping effect in the print (reversed effect)
I ask this because the photos he posted looked like warping not cupping. and just want to make sure we are all on the same page.
I planned on printing a large 180x180 square (my bed is only 200x200) just ran into some other issues i have to get sorted first… the objects he printed before were confirmed to be smaller objects like the ones i was printing without issue.
I am not saying that the effect you have noticed is non existent... i wont know until i print a larger object.... but that after what i seen last night he has some other issues to get sorted before making a conclusion about any warping or cupping.
When he can print without other issues... then a determination about cupping can be made.
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My PEI bed, if left un-clamped, but oriented the way it is on the build plate, has a concave top, and a convex bottom – IE the edges of the PEI plate curl upwards. When clamped down, the plate is flat to about 50-100 microns. When printing, eg, a large hollow cylinder with a diameter that occupies a large part of the build plate, the print adheres fine entirely through the print. The edges of the circle are touching the build plate, as well as the middle of the circle. However, when the print is removed, there is a noticeable convex surface on the bottom of the print. If you now place the object (cylinder) on the bed, the center of the circle is touching the build plate, and the object would have a tendency to rock around. IE there is a "bulge" on the bottom of the print, approximately equal to the curvature of the print surface when unclamped. The warping does not occur during the print, seemingly the PEI "holds" the print down enough to resist this -- but when the part is removed, the condition presents itself.
It's easily fixed by heating up the bottom of the part, and pushing it flat against a surface plate. It's odd, and I'm wondering if the phenomenon I sometimes see is the same as was described here.
